The present application relates to a light emitting diode, a method of manufacturing a light emitting diode, a light emitting diode backlight, a light emitting diode illuminating device, a light emitting diode display, and an electronic apparatus.
In the past, GaN-based light emitting diodes like one shown in FIG. 20 have been known. Referring to FIG. 20, in this GaN-based light emitting diode, an n-GaN layer 102, an active layer 103 and a p-GaN layer 104 are sequentially deposited over a sapphire substrate 101 to form a light emitting diode structure. In this structure, upper part of the n-GaN layer 102, the active layer 103 and the p-GaN layer 104 are patterned by etching into a pillar shape having an end face perpendicular to the substrate face. Furthermore, a p-electrode 105 is formed on the p-GaN layer 104 and an n-electrode 106 is formed on the n-GaN layer 102 outside the pillar-shaped part. In the operation of the GaN-based light emitting diode, light emanated from the active layer 103 repeats total reflection inside the pillar-shaped part and passes through the sapphire substrate 101, followed by being extracted to the outside finally.
As one related art, a technique has been proposed in Japanese Patent Laid-Open No. 2002-50792 for example. This patent discloses a semiconductor light emitting diode that includes an electrically conductive substrate, a semiconductor light emitting layer epitaxially grown on the conductive substrate, and a metal electrode on the opposite side of the conductive substrate across the semiconductor light emitting layer. In this diode, the metal electrode is disposed so that light emanated from the semiconductor light emitting layer is reflected by the metal electrode toward the external, and for example the metal electrode face is inclined at 45 degrees to the semiconductor light emitting layer. It however should be noted that this proposed diode is greatly different in the technical idea from light emitting diodes according to embodiments of the present invention, in which semiconductor layers constructing a light emitting diode structure have an end face inclined to the major face of the semiconductor layers, and a reflector opposed to the end face is provided.
In the conventional GaN-based light emitting diode shown in FIG. 20, since the end face of the pillar-shaped part formed of the n-GaN layer 102, the active layer 103 and the p-GaN layer 104 is perpendicular to the substrate face, light emanated from the active layer 103 in the operation of the diode repeats total reflection inside the pillar-shaped part, and is absorbed as the result thereof. This leads to low light extraction efficiency, which results in decreased emission efficiency. In addition, this GaN-based light emitting diode involves a drawback in that the diameter of the pillar-shaped part formed of the n-GaN layer 102, the active layer 103 and the p-GaN layer 104 is generally as large as about 300 μm, and therefore the total diode size is large.
Therefore, there is a need to provide a light emitting diode that allows a great improvement of the light extraction efficiency to thereby significantly enhance the emission efficiency, and can easily achieve a miniaturized size.
Moreover, there is a need to provide a light emitting diode backlight, a light emitting diode illuminating device, a light emitting diode display and an electronic apparatus that employ this excellent light emitting diode.